Narrative: 
In order to generate a PDDL types expression
As a software component
I want to generate compliant PDDL types expression from domain objects

Scenario: Two objects, a location and a crane
Given a location locA
And a crane craneA in locA
And I register all these objects
When I ask for the types
Then The resulting expression is '(:TYPES LOCATION CRANE)'

Scenario: No objects
When I ask for the types
Then I get an empty expression